Preheat the oven to 220°C/fan 200°C/gas mark 7. Add 1 tbsp oil to a 24cm heavy-bottomed, high-sided, ovenproof frying pan and place in the oven for 10 minutes.
Meanwhile, combine the flour and pepper in a medium bowl, making a well in the centre. Whisk the milk and 2 eggs together in a jug, then gradually add the liquid mixture to the flour, whisking until completely smooth. Leave to sit for 5 minutes.
Remove the pan from the oven and swirl the oil in the pan to coat. Add the batter to the pan and transfer to the oven. Bake for 25 minutes, until the pancake is puffed and golden.
Meanwhile, place a large griddle pan over a medium/high heat and add the bacon while the pan is still cold. Cook for 3-4 minutes on one side, then turn over to cook for a further 3-4 minutes, until cooked through and a little crispy. During the last few minutes, add the tomatoes to the pan and cook, turning often, until blistered but still holding their shape. Transfer everything to a plate and keep warm.
Add 1 tbsp oil to a large, non-stick frying pan and place over a medium heat. Once hot, add the mushrooms and cook for 4-5 minutes, shaking occasionally until the mushrooms are tender and a crispy golden brown. Transfer to a bowl and season well, tossing with the parsley. Keep warm.
Wipe the frying pan clean and add the remaining oil. Place over a medium high heat and, once hot, crack in the last egg. Fry for 4-5 minutes until crispy underneath, the white is cooked and the yolk is still runny.
Once the pancake is cooked, remove from the oven and wait for the puffed centre to settle down. Once it’s more level, add the fry-up ingredients to the centre and season to serve.